The health effects of light on the skin are well known. Ultraviolet (UV) light causes DNA damage and precancerous growths and is the primary risk factor for most skin cancers.
As much as 80% of skin aging is thought to result from sun exposure.1 On the other hand, UV light exerts anti-inflammatory, immunomodulatory effects that have been exploited for decades in office and home-based targeted phototherapy treatments for inflammatory skin conditions, notably eczema and psoriasis.
Visible light is essential to our perception of skin. “Good lighting†impacts how we see ourselves and others on social media posts and in Zoom meetings. Dermatologists use powerful LED exam lights every day during skin cancer screenings. We use hand-held gadgets called dermatoscopes that magnify and polarize light to evaluate pigmented lesions.
Visible light can also be therapeutic. Light amplification by stimulated emission of radiation (L.A.S.E.R.) devices deliver high-intensity light to the skin preferentially targeting specific structures. Laser light is special light: it is monochromatic (one color), collimated (nondivergent) and coherent (in phase).
Increasingly we use lasers to treat a variety of medical and cosmetic skin conditions. Dermatology laser treatments are at the intersection of physics and biology, technology and physiology.
Rosacea and Red Skin
Rosacea is a skin condition that affects more than 16 million Americans.2 Rosacea patients suffer with a range of symptoms from inflammatory papules and pustules to flushing, from generalized facial redness and broken capillaries to fibro sebaceous overgrowth of nose tissue known as rhinophyma.
We have traditionally identified rosacea in patients of northern European descent. New data, however, suggest we have been missing individuals of Asian, Latinx and African ancestry suffering with this vexing skin condition.3
While patients may require topical and oral medications for inflammatory papules and pustules, lasers are the treatment of choice to reduce facial redness and capillaries. (See Figure 1) Vascular lasers, often yellow or green light, target hemoglobin. Historically, these lasers were set to energy parameters that boiled the blood so rapidly vessels would burst resulting in bruises, purpura. Purpura lasts for weeks. Patients hated the downtime and would occasionally blister or even scar.
More recently, though, we learned to set lasers to parameters that deliver energy more slowly, treating to new clinical endpoints like transient purpura, just below the bruising threshold. Patients have better outcomes with less downtime. We use a similar approach with serial, non-purpuric treatments to improve red stretch marks, red scars and red marks from acne.
Bruising settings remain the standard of care for many red bumps and birthmarks. Cherry angiomas, specking the trunk of almost every 50-yr old, and venous lakes, the soft lumps on the lips of some seniors, are two common conditions treated with bruising settings. Vascular birthmarks, notably port wine stains and infantile hemangiomas, also typically require purpura to improve.
Whether bruised or not bruised, the principle of vascular laser treatment is the same: target hemoglobin with laser light, boil blood, destroy the target and let the skin recover.
Dermatoheliosis and Brown Spots
Sun damage. This includes solar lentigines or sun freckles. Other common “brown spots†are seborrheic keratoses. These are actually benign epidermal tumors associated with age, sun exposure and a variety of somatic mutations. Still other brown spots are melanomas, the most deadly skin cancer. A lentigo maligna melanoma can look remarkably like a benign sun freckle. Distinguishing pigmented lesions and detecting melanoma early remains one of the most important aspects of dermatology as a specialty.
Once melanoma is ruled out, consider pigment lasers. These lasers target melanin with rapid, high-powered packets of energy. Laser light, often red or infrared, heats target pigment. In the process, tissue water is boiled, causing steam bubbles to form within the skin.
For some, the entire face, chest or neck develops so many sun freckles the skin appears dull and mottled. Fractionated lasers target pigment with tiny columns of infrared light, creating pinpoint channels. Pigment is then transepidermally eliminated though these channels. Ultimately, skin tone improves as it is unburdened of abnormal pigment from years of sun damage. (See Figure 2)
Pigment lasers remove tattoo ink in the same way they target melanin in brown spots. Newer picosecond technology allows faster pulses that are not only more efficient at mobilizing tiny ink particles, but also more effective for a wider range of tattoos including aqua and turquoise – colors we could rarely remove in the past. These picosecond lasers typically require fewer treatments with less downtime.
As many as 47% of millennials have a least one tattoo.4 As tattoo incidence increases, we are seeing more allergic reactions to tattoo ink. Instead of long-term topical or injected steroid treatments, we are now combining multiple lasers to treat these cutaneous hypersensitivity reactions. Pigment lasers break up and mobilize tattoo ink, then infrared lasers release it through tiny laser-cut channels in the skin. Careful attention to laser parameters is critical to great outcomes.
Hair
It has been 25 years since the FDA approved the first laser for hair reduction.5 Laser light, often infrared, targets melanin within brown or black hairs. The heat energy shocks or destroys follicular stem cells and hair is reduced. Over the years, these lasers have become faster, safer and increasingly efficient. Treatments have gradually shifted from being performed primarily in dermatology clinics by doctors, increasingly to medispas by non-physician operators.
Unfortunately, the proportion of laser-related injuries has increased. Blisters, permanent pigmentary change and scarring are among the adverse outcomes making hair removal the number one laser procedure for malpractice claims.6
Infrared lasers are dermatologists’ treatment of choice for razor bumps and some forms of folliculitis. We can also use these devices to treat pilonidal cysts, a condition that recurs frequently with traditional surgery. In addition, laser hair reduction is a useful adjunct treatment in some cases of hidradenitis suppurativa, an inflammatory condition affecting the pilosebaceous unit.
In the future, we will have lasers that treat red and blond hair as well as fine, peach fuzz vellus hairs and better understand why laser treatments result in permanent hair removal in some and temporary reduction in others.
Acne Scars
Acne is dermatology’s bread and butter. We have washes and creams and pills and peels. We have lasers and light-activated drugs. We have nutritional recommendations and hormonal interventions.
Despite so many treatment options, 43% of acne patients end up with scarring.7 Long after we clear acne, the skin often remains marred by brown marks, red spots and/or textured scars.
The scars and scar erythema left in the wake of inflammatory and cystic acne need a solution. The scars themselves are in the dermis, well beneath the depth of penetration for microdermabrasion and most chemical peels. Enter infrared lasers, fractionated erbium and CO2 devices that heat columns of skin through to collagen in the reticular dermis.
Some devices actually heat tissue to the point it vaporizes. Heated columns of collagen contract, denature and are ultimately replaced by new tissue. This remodeling process leaves laser-treated acne scars with a smoother appearance.
Isotretinoin (previously branded Accutane) is the most potent treatment for cystic acne. This drug can permanently alter sebaceous glands and put acne into remission. The dogma had been lasers must be avoided for a least one year after completing isotretinoin.
Beginning laser treatment earlier was thought to carry significant risk of hypertrophic scarring. It turns out, this thinking may have been based on anecdotal evidence in a case report on dermabrasion,8 which is not laser, and the scars may have resulted from the acne itself rather than the procedure.
A growing body of data from large studies across the globe suggest laser treatments can be performed safely immediately post-isotretinoin and even while on the drug.9, 10, 11 Moreover, certain laser treatments seem to improve both acne and acne scarring. In sum, we are moving toward routine, simultaneous treatment of acne and acne scarring.
Surgical and Traumatic Scars
What about other types of scars? For years surgeons passively waited six to 12 months or longer before considering interventions like dermabrasion, intralesional steroid injections or laser. Moreover, surgeons generally reserved lasers for red scars.
A paradigm shift is occurring as new data emerges. Early intervention with fractionated laser devices may prevent hypertrophic scars.12 In some studies, authors performed serial treatments starting the day of suture removal. Several split scar studies where one half of a scar is randomized to receive laser treatment and the other half serves as a control, show that treated scars ultimately scar less than the side left to remodel passively.13 (See Figure 3) The newest data even suggest that pre-treating skin prior to surgery results in better-looking scars.14
While the story of lasers and scars is still being written, I share a simple rule of thumb with medical and surgical colleagues. The time to think about laser for traumatic scars is at re-epithelialization, for surgical scars it is at suture removal. Early intervention is key.
Finding photomedical solutions to an ever-expanding array of skin conditions is the best part of my job as a laser dermatologist. We have understood laser physics for some time. Now we have entered an age in dermatology where a deeper understanding of laser tissue interactions allows more precise treatments across a greater range of skin types in the management of an expanding list of medical and cosmetic skin conditions.
In the future, we will continue to combine these devices with topical and oral medications to optimize treatment outcomes. We will routinely synergize laser treatments with drug therapies and utilize multiple devices concurrently or sequentially in well-established algorithms. The future of lasers in dermatology is bright.
Jason A. Clark, MD, FAAD
Dr. Clark is an adjunct assistant professor of dermatology at Emory University and founder of Clark Laser & Cosmetic Dermatology. He completed medical school at Duke, his dermatology residency at Emory and a photomedicine fellowship in laser and cosmetic dermatology at Massachusetts General Hospital/Harvard Medical School. Dr. Clark provides specialized laser, cosmetic and photomedical dermatologic care to patients in Georgia and throughout the Southeast.
References
1. Uitto J. Understanding premature skin aging. N Engl J Med, 1997; 337: 1463.
2. National Rosacea Society; www.rosacea.org. Accessed June 3, 2020.
3. Alexis, et al. Global epidemiology and clinical spectrum of rosacea, highlighting skin of color: review and clinical practice experience. JAAD, 2019 June; 80 (6): 1722-1729.e7.
4. Shannon-Missal L. Tattoo takeover: three in ten Americans have tattoos, and most don’t stop at just one. The Harris Poll #12, 2016 Feb; https://theharrispoll.com. Accessed June 3, 2020.
5. Grossman M, Dierickx C, Farinelli W, et al. Damage to hair follicles by normal-mode ruby laser pulses. JAAD, 1996; 35: 889–94.
6. Jalian HR, Jalian CA, Avram MM. Common causes of injury and legal action in laser surgery. JAMA Derm, 2013 Feb; 149 (2): 188-93.
7. Dreno B. Evaluation of the prevalence, risk factors, clinical characteristics, and burden of acne scars among active acne patients in Brazil, France, and the USA. Abstract. JAAD, 2017; 76 (6): supplement 1, AB132.
8. Katz BE and Mac Farlane DF. Atypical facial scarring after isotretinoin therapy in a patient with previous dermabrasion. JAAD, 1994 May; 30 (5 Pt2): 852-3.
9. Chandrashekar, et al. Safety of performing invasive acne scar treatment and laser hair removal in patients on oral isotretinoin: a retrospective study of 110 patients. International Journal of Dermatology, 2014; 53: 1281-1285.
10. Yoon, et al. Concomitant use of an infrared fractional laser with low-dose isotretinoin for the treatment of acne and acne scars. Journal of Dermatological Treatment, 2014; 25: 142-146.
11. Kim, et al. The safe delivery of fractional ablative carbon dioxide laser treatment for acne scars in Asian patients receiving oral isotretinoin. Derm Surg, 2014; 40: 1361-1366.
12. Choe, et al. Prevention of thyroidectomy scar using a new 1,550-nm fractional erbium-glass laser. Derm Surg, 2009; 35: 1199-1205.
13. Safra, et al. Early intervention with pulse dye and CO2 ablative fractional lasers to improve cutaneous scarring post-lumpectomy: a randomized controlled trial on the impact of intervention of final cosmesis. Laser in Med Sci, 2019; 34: 1881-1887.
14. Friedman, et al. Laser pretreatment for the attenuation of planned surgical scars: a randomized self-controlled hemi-scar pilot study. JPRAS, 2020; 73: 893-898.
